Lack of the IFN-γ signal leads to lethal Orientia tsutsugamushi infection in mice with skin eschar lesions.

Scrub typhus is an acute febrile disease due to Orientia tsutsugamushi (Ot) infection and can be life-threatening with organ failure, hemorrhage, and fatality. Yet, little is known as to how the host reacts to Ot bacteria at early stages of infection; no reports have addressed the functional roles of type I versus type II interferon (IFN) responses in scrub typhus. In this study, we used comprehensive intradermal (i.d.) inoculation models and two clinically predominant Ot strains (Karp and Gilliam) to uncover early immune events. Karp infection induced sequential expression of Ifnb and Ifng in inflamed skin and draining lymph nodes at days 1 and 3 post-infection. Using double Ifnar1-/-Ifngr1-/- and Stat1-/- mice, we found that deficiency in IFN/STAT1 signaling resulted in lethal infection with profound pathology and skin eschar lesions, which resembled to human scrub typhus. Further analyses demonstrated that deficiency in IFN-γ, but not IFN-I, resulted in impaired NK cell and macrophage activation and uncontrolled bacterial growth and dissemination, leading to metabolic dysregulation, excessive inflammatory cell infiltration, and exacerbated tissue damage. NK cells were found to be the major cellular source of innate IFN-γ, contributing to the initial Ot control in the draining lymph nodes. In vitro studies with dendritic cell cultures revealed a superior antibacterial effect offered by IFN-γ than IFN-ß. Comparative in vivo studies with Karp- and Gilliam-infection revealed a crucial role of IFN-γ signaling in protection against progression of eschar lesions and Ot infection lethality. Additionally, our i.d. mouse models of lethal infection with eschar lesions are promising tools for immunological study and vaccine development for scrub typhus.

[High Resolution Emission Inventory of Greenhouse Gas and Its Characteristics in Guangdong，China].

Based on the typical city survey data and statistics of Guangdong Province， a 2018-based 3 km×3 km gridded greenhouse gas emissions inventory was developed for Guangdong Province using the combination of top-down and bottom-up emission factor methods. The inventory covered the CO2， CH4， and N2O emissions from energy， industrial processes， agriculture， land use change and forest， waste management， and indirect sources. The results showed that estimates for CO2， CH4， and N2O in Guangdong Province for the year 2018 were 8.5×108， 1.9×106， and 1.1×105 t， respectively， and 8.5×108， 4.0×107， and 3.4×107 t by equivalent carbon dioxide， totaling 9.2×108 t. CO2 was the main greenhouse gas in Guangdong Province， accounting for 92.0% of the total emissions. Energy and indirect sources were the main emission sources， accounting for 77.9% and 7.6%， respectively， totaling 85.5%. Spatial distributions illustrated that most grids were greenhouse gas emissions， whereas some others were greenhouse gas sinks； the greenhouse gas emissions were distributed mainly in the Pearl River Delta region and had certain characteristics of distribution along the road network and channels. The greenhouse gas grids of high emission were mainly the locations of high energy-consuming enterprises such as large power plants， steel mills， and cement plants.

CD8 + T cell response promotes viral clearance and reduces chances of severe testicular damage in mouse models of long-term Zika virus infection of the testes.

Zika virus (ZIKV) causes human testicular inflammation and alterations in sperm parameters and causes testicular damage in mouse models. The involvement of individual immune cells in testicular damage is not fully understood. We detected virus in the testes of the interferon (IFN) α/ß receptor -/- A129 mice three weeks post-infection and found elevated chemokines in the testes, suggesting chronic inflammation and long-term infection play a role in testicular damage. In the testes, myeloid cells and CD4 + T cells were absent at 7 dpi but were present at 23 days post-infection (dpi), and CD8 + T cell infiltration started at 7 dpi. CD8 -/- mice with an antibody-depleted IFN response had a significant reduction in spermatogenesis, indicating that CD8 + T cells are essential to prevent testicular damage during long-term ZIKV infections. Our findings on the dynamics of testicular immune cells and importance of CD8 + T cells functions as a framework to understand mechanisms underlying observed inflammation and sperm alterations in humans.

Differential cellular immune responses against Orientia tsutsugamushi Karp and Gilliam strains following acute infection in mice.

Scrub typhus is a leading cause of febrile illness in endemic countries due to infection with Orientia tsutsugamushi (Ot), a seriously understudied intracellular bacterium. Pulmonary involvement associated with vascular parasitism in patients is common and can develop into life threatening interstitial pneumonia. The diverse antigenicity of Ot genotypes and inter-strain differences in genome content are connected to varied virulence and clinical outcomes; however, detailed studies of strain-related pulmonary immune responses in human patients or small animal models of infection are lacking. In this study, we have used two clinically prevalent bacterial strains (Karp and Gilliam) to reveal cellular immune responses in inflamed lungs and potential biomarkers of disease severity. The results demonstrate that outbred CD-1 mice are highly susceptible to both Karp and Gilliam strains; however, C57BL/6 (B6) mice were susceptible to Karp, but resistant to Gilliam (with self-limiting infection), corresponding to their tissue bacterial burdens and lung pathological changes. Multicolor flow cytometric analyses of perfused B6 mouse lungs revealed robust and sustained influx and activation of innate immune cells (macrophages, neutrophils, and NK cells), followed by CD4+ and CD8+ T cells, during Karp infection, but such responses were greatly attenuated during Gilliam infection. The robust cellular responses in Karp-infected B6 mice positively correlated with significantly early and high levels of serum cytokine/chemokine protein levels (CXCL1, CCL2/3/5, and G-CSF), as well as pulmonary gene expression (Cxcl1/2, Ccl2/3/4, and Ifng). In vitro infection of B6 mouse-derived primary macrophages also revealed bacterial strain-dependent immune gene expression profiles. This study provided the lines of evidence that highlighted differential tissue cellular responses against Karp vs. Gilliam infection, offering a framework for future investigation of Ot strain-related mechanisms of disease pathogenesis vs. infection control.

Maximizing ozone control by spatial sensitivity-oriented mitigation strategy in the Pearl River Delta Region, China.

The Pearl River Delta (PRD) has long been plagued by severe O3 pollution, particularly during the autumn. A regional O3 pollution episode influenced by the Western Pacific Subtropical High in September 2021 was characterized by near-surface O3 escalation due to strong photochemical reactions within the planetary boundary layer. This event was targeted to develop effective control strategies through investigation of precursor control type and scope based on the high-order decoupled direct method (HDDM) and integrated source apportionment method (ISAM) of CMAQ. Generally, the majority of areas (67.0 %) were under NOx-limited regime, which should strengthen afternoon NOx control inferred by positive convex O3 responses. However, high emission and heavily polluted areas located in central PRD were under VOC-limited regime (11.6 %) or mixed regime (15.0 %). The remaining areas (6.4 %) were under NOx-titration or insensitive conditions. Regarding source apportionment, Guangdong province contributed 32.3 %-58.4 % to MDA8 O3 of PRD, especially higher proportion (>50 %) to central areas. Overall, local-focused NOx/VOC emission reductions had limited effects on O3 mitigation for receptor cities compared to regional-cooperative regulation. When region-wide VOC emission reduction was implemented, MDA8 O3 in VOC-limited grids exhibited the largest declines (2.3 %-4.1 %, 3.9- 7.0 µg·m-3). However, unified NOx control contributed to increasing MDA8 O3 in VOC-limited grids (most stations located for air quality evaluation) whereas decreased MDA8 O3 by 2.1 %- 5.7 %, 3.0- 8.2 µg·m-3 in large-scale NOx-limited grids. The sensitivity-oriented regional control avoided O3 rebound and achieved the greatest decline of 3.4 %- 5.0 %, 5.7- 8.4 µg·m-3 in VOC-limited grids; additionally, time-refined dynamic aggressive NOx control decreased peak O3 by an extra 1.2- 6 µg·m-3, both of which facilitate the regulation for the forecasting O3 episodes. These findings suggest that in heavily polluted environments, the enhancement of O3 regulation benefits requires meticulous, coordinated, and dynamic NOx and VOC controls spanning the entire region based on high-resolution analysis of heterogeneous O3-NOx-VOC sensitivity. Furthermore, emission reduction gains should be more reasonably reflected through increasing in-situ observations covering multi-sensitivity regions.

Metformin restrains ZIKV replication and alleviates virus-induced inflammatory responses in microglia.

The re-emergence of Zika virus (ZIKV) remains a major public health threat that has raised worldwide attention. Accumulating evidence suggests that ZIKV can cause serious pathological changes to the human nervous system, including microcephaly in newborns. Recent studies suggest that metformin, an established treatment for diabetes may play a role in viral infection; however, little is known about the interactions between ZIKV infection and metformin administration. Using fluorescent ZIKV by flow cytometry and immunofluorescence imaging, we found that ZIKV can infect microglia in a dose-dependent manner. Metformin diminished ZIKV replication without the alteration of viral entry and phagocytosis. Our study demonstrated that metformin downregulated ZIKV-induced inflammatory response in microglia in a time- and dose-dependent manner. Our RNA-Seq and qRT-PCR analysis found that type I and III interferons (IFN), such as IFNα2, IFNß1 and IFNλ3 were upregulated in ZIKV-infected cells by metformin treatment, accompanied with the downregulation of GBP4, OAS1, MX1 and ISG15. Together, our results suggest that metformin-mediated modulation in multiple pathways may attribute to restraining ZIKV infection in microglia, which may provide a potential tool to consider for use in unique clinical circumstances.

Alterations in germinal center formation and B cell activation during severe Orientia tsutsugamushi infection in mice.

Scrub typhus is a poorly studied but life-threatening disease caused by the intracellular bacterium Orientia tsutsugamushi (Ot). Cellular and humoral immunity in Ot-infected patients is not long-lasting, waning as early as one-year post-infection; however, its underlying mechanisms remain unclear. To date, no studies have examined germinal center (GC) or B cell responses in Ot-infected humans or experimental animals. This study was aimed at evaluating humoral immune responses at acute stages of severe Ot infection and possible mechanisms underlying B cell dysfunction. Following inoculation with Ot Karp, a clinically dominant strain known to cause lethal infection in C57BL/6 mice, we measured antigen-specific antibody titers, revealing IgG2c as the dominant isotype induced by infection. Splenic GC responses were evaluated by immunohistology, co-staining for B cells (B220), T cells (CD3), and GCs (GL-7). Organized GCs were evident at day 4 post-infection (D4), but they were nearly absent at D8, accompanied by scattered T cells throughout splenic tissues. Flow cytometry revealed comparable numbers of GC B cells and T follicular helper (Tfh) cells at D4 and D8, indicating that GC collapse was not due to excessive death of these cell subtypes at D8. B cell RNAseq analysis revealed significant differences in expression of genes associated with B cell adhesion and co-stimulation at D8 versus D4. The significant downregulation of S1PR2 (a GC-specific adhesion gene) was most evident at D8, correlating with disrupted GC formation. Signaling pathway analysis uncovered downregulation of 71% of B cell activation genes at D8, suggesting attenuation of B cell activation during severe infection. This is the first study showing the disruption of B/T cell microenvironment and dysregulation of B cell responses during Ot infection, which may help understand the transient immunity associated with scrub typhus.

A Microphysiological Device to Model the Choriodecidual Interface Immune Status during Pregnancy.

During human pregnancy the chorion (fetal) lines decidua (maternal) creating the feto-maternal interface. Despite their proximity, resident decidual immune cells remain quiescent during gestation and do not invade the chorion. Infection and infiltration of activated immune cells toward the chorion are often associated with preterm birth. However, the mechanisms that maintain choriodecidual immune homeostasis or compromise immune barrier functions remain unclear. To understand these processes, a two-chamber microphysiological system (MPS) was created to model the human choriodecidual immune interface under normal and infectious conditions in vitro. This MPS has outer (fetal chorion trophoblast cells) and inner chambers (maternal decidual + CD45+ cells [70:30 ratio]) connected by microchannels. Decidual cells were treated with LPS to mimic maternal infection, followed by immunostaining for HLA-DR and HLA-G, immune panel screening by imaging cytometry by time of flight, and immune regulatory factors IL-8 and IL-10, soluble HLA-G, and progesterone (ELISA). LPS induced a proinflammatory phenotype in the decidua characterized by a decrease in HLA-DR and an increase in IL-8 compared with controls. LPS treatment increased the influx of immune cells into the chorion, indicative of chorionitis. Cytometry by time of flight characterized immune cells in both chambers as active NK cells and neutrophils, with a decrease in the abundance of nonproinflammatory cytokine-producing NK cells and T cells. Conversely, chorion cells increased progesterone and soluble HLA-G production while maintaining HLA-G expression. These results highlight the utility of MPS to model choriodecidual immune cell infiltration and determine the complex maternal-fetal crosstalk to regulate immune balance during infection.

Intrinsic STING Switches off Pathogenetic Programs of Th1 Cells to Inhibit Colitis.

BACKGROUND & AIMS: T helper 1 (Th1) effector cells are implicated in inflammatory bowel disease. The stimulator of interferon genes (STING), an intracellular DNA sensor, has been shown to regulate infection and various cancers. However, whether and how intrinsic STING signaling in Th1 cells regulates colitis is still unknown. METHODS: Dextran sodium sulfate-induced colitis and wild-type/STING-deficient CD4+T cell adoptive transfer models were used to analyze the role of STING in regulating colitis. The effect of STING on Th1 cells was determined by flow cytometry, RNA sequencing, metabolic assays, and mitochondrial functions. 16S ribosomal RNA sequencing and germ-free mice were used to investigate whether the microbiota were involved. The in vivo effect of STING agonist in murine colitis was determined. The expression and role of STING in human T cells were also determined. RESULTS: Activation of STING transformed proinflammatory IFNγ+Th1 cells into IL-10+IFNγ+Th1 cells, which were dramatically less pathogenic in inducing colitis. STING promoted Th1 interleukin (IL)-10 production by inducing STAT3 translocation into nuclear and mitochondria, which promoted Blimp1 expression and mitochondrial oxidation, respectively. Blockade of glucose or glutamine-derived oxidation, but not lipid-derived oxidation, suppressed STING induction of IL-10. Gut microbiota were changed in STING-/- mice, but the altered microbiota did not mediate STING effects on intestinal CD4+T cell production of IL-10. Translationally, STING agonists suppressed both acute and chronic colitis. Intestinal STING+ CD4+T cells were increased in inflammatory bowel disease patients, and STING agonists upregulated IL-10 production in human CD4+T cells. CONCLUSIONS: These findings establish a crucial role of T cell-intrinsic STING in switching off the pathogenic programs of Th1 cells in intestinal inflammation.

B cell-specific mAb-siRNA conjugates improve experimental myasthenia.

Myasthenia gravis (MG) is a debilitating autoimmune disease characterized by muscle fatigue and weakness caused by autoantibody- and complement-mediated damage to the neuromuscular junction. This study sought to compare the efficacy of unique sets of monoclonal antibody-siRNA conjugates, individually (mono) or in combination (duo), against the crucial receptors predominantly or solely expressed on two subsets of B cells-plasma B cells and their precursor (transitional mature B) cells in a mouse model of MG. At the optimized doses, the conjugates, likely due to the combined activities of mAb and siRNA, substantially decreased the expression levels of CD268 (B cell-activating factor receptor) in mature B cells and CD269 (B-cell maturation antigen) in plasma cells concomitantly with reducing the levels of acetylcholine receptor (AChR)-specific autoantibodies. PEGylation, but not pretreatment with an antibody against type 1 interferon receptor, further improved duoconjugate-induced reduction in the autoantibody levels. Our results show that the duoconjugate treatment significantly improved the clinical symptoms of MG, consistent with the preservation of bungarotoxin-bound functional AChRs. In the future, developing similar target-specific combination molecules can potentially turn into a new and effective therapeutic approach for MG.

Dual spike and nucleocapsid mRNA vaccination confer protection against SARS-CoV-2 Omicron and Delta variants in preclinical models.

Emergence of SARS-CoV-2 variants of concern (VOCs), including the highly transmissible Omicron and Delta strains, has posed constant challenges to the current COVID-19 vaccines that principally target the viral spike protein (S). Here, we report a nucleoside-modified messenger RNA (mRNA) vaccine that expresses the more conserved viral nucleoprotein (mRNA-N) and show that mRNA-N vaccination alone can induce modest control of SARS-CoV-2. Critically, combining mRNA-N with the clinically proven S-expressing mRNA vaccine (mRNA-S+N) induced robust protection against both Delta and Omicron variants. In the hamster models of SARS-CoV-2 VOC challenge, we demonstrated that, compared to mRNA-S alone, combination mRNA-S+N vaccination not only induced more robust control of the Delta and Omicron variants in the lungs but also provided enhanced protection in the upper respiratory tract. In vivo CD8+ T cell depletion suggested a potential role for CD8+ T cells in protection conferred by mRNA-S+N vaccination. Antigen-specific immune analyses indicated that N-specific immunity, as well as augmented S-specific immunity, was associated with enhanced protection elicited by the combination mRNA vaccination. Our findings suggest that combined mRNA-S+N vaccination is an effective approach for promoting broad protection against SARS-CoV-2 variants.

[Effects of Tropical Cyclones on Ozone Pollution in the Pearl River Delta in Autumn].

Based on the tropical cyclone track data in the northwest Pacific Ocean from 2015 to 2020, meteorological observation data, and ozone concentration monitoring data in the Pearl River Delta (PRD), the impacts of four tropical cyclones, namely the westbound tropical cyclone (type A), East China Sea tropical cyclone (type B), offshore tropical cyclone (type C), and offshore tropical cyclone (type D), on ozone concentration in the PRD were analyzed. The results showed that:under the influence of the type A tropical cyclone, the risk of regional ozone concentration exceeding the standard exhibited little change. Under the influence of the type B tropical cyclone, the risk of ozone exceeding the standard in the PRD was obviously increased. Under the influence of the type C tropical cyclone, the risk of regional ozone exceeding the standard obviously increased, but the increase was weaker than that of the type B tropical cyclone. The type D tropical cyclone was far away from the Chinese mainland and had little influence on ozone concentration in the PRD. When the type A or type C tropical cyclones occurred, the average daily maximum 8-hour average ozone concentration (MDA8) in the PRD region increased by approximately 5 µg·m-3, and the ozone MDA8 in some cities may have decreased. When the type B tropical cyclone occurred, the regional ozone MDA8 increased by 19 µg·m-3 on average, and the ozone concentration in all cities increased significantly. Among them, the average increase in ozone MDA8 in Zhuhai and Jiangmen was relatively large, with an increase of greater than 20 µg·m-3. Generally speaking, the ozone concentration in cities in the western PRD was more affected by tropical cyclones. When the type B tropical cyclone occurred, solar radiation increased, sunshine duration lengthened, cloud cover decreased, air temperature rose, and relative humidity decreased in the PRD, all of which were beneficial to photochemical reactions. Meanwhile, downward flow increased in the boundary layer, and downward flow transported high-concentration ozone to the ground, which promoted the increase in ozone concentration on the ground. When type A or type C tropical cyclones occurred, the change in meteorological conditions was not entirely conducive to the increase in ozone concentration, and in some cases, even adverse meteorological conditions such as rainfall occurred, which led to the risk of regional ozone exceeding the standard being less than that of the type B tropical cyclone. Affected by tropical cyclones, sunshine hours and air temperature in western cities of the PRD increased more than those in eastern cities, which was more conducive to ozone generation.

Distinct Role of TNFR1 and TNFR2 in Protective Immunity Against Orientia tsutsugamushi Infection in Mice.

Infection with Orientia tsutsugamushi, an obligate intracellular bacterium, can cause mild or severe scrub typhus. Some patients develop acute lung injury, multi-organ failure, and fatal infection; however, little is known regarding key immune mediators that mediate infection control or disease pathogenesis. Using murine models of scrub typhus, we demonstrated in this study the requirement of TNF-TNFR signaling in protective immunity against this infection. Mice lacking both TNF receptors (TNFR1 and TNFR2) were highly susceptible to O. tsutsugamushi infection, displaying significantly increased tissue bacterial burdens and succumbing to infection by day 9, while most wild-type mice survived through day 20. This increased susceptibility correlated with poor activation of cellular immunity in inflamed tissues. Flow cytometry of lung- and spleen-derived cells revealed profound deficiencies in total numbers and activation status of NK cells, neutrophils, and macrophages, as well as CD4 and CD8 T cells. To define the role of individual receptors in O. tsutsugamushi infection, we used mice lacking either TNFR1 or TNFR2. While deficiency in either receptor alone was sufficient to increase host susceptibility to the infection, TNFR1 and TNFR2 played a distinct role in cellular responses. TNF signaling through TNFR1 promoted inflammatory responses and effector T cell expansion, while TNFR2 signaling was associated with anti-inflammatory action and tissue homeostasis. Moreover, TNFRs played an intrinsic role in CD8+ T cell activation, revealing an indispensable role of TNF in protective immunity against O. tsutsugamushi infection.

The Protective Role of IL-36/IL-36R Signal in Con A-Induced Acute Hepatitis.

The IL-36 family, including IL-36α, IL-36ß, IL-36γ, and IL-36R antagonist, belong to the IL-1 superfamily. It was reported that IL-36 plays a role in immune diseases. However, it remains unclear how IL-36 regulates inflammation. To determine the role of IL-36/IL-36R signaling pathways, we established an acute hepatitis mouse model (C57BL/6) by i.v. injection of the plant lectin Con A. We found that the levels of IL-36 were increased in the liver after Con A injection. Our results demonstrated the infiltrated neutrophils, but not the hepatocytes, were the main source of IL-36 in the liver. Using the IL-36R-/- mouse model (H-2b), we surprisingly found that the absence of IL-36 signals led to aggravated liver injury, as evidenced by increased mortality, elevated serum alanine aminotransferase and aspartate aminotransferase levels, and severe liver pathological changes. Further investigations demonstrated that a lack of IL-36 signaling induced intrahepatic activation of CD4+ and CD8+ T lymphocytes and increased the production of inflammatory cytokines. In addition, IL-36R-/- mice had reduced T regulatory cell numbers and chemokines in the liver. Together, our results from the mouse model suggested a vital role of IL-36 in regulating T cell function and homeostasis during liver inflammation.

IL-33 activates mTORC1 and modulates glycolytic metabolism in CD8+ T cells.

Interleukin (IL)-33, a member in the IL-1 family, plays a central role in innate and adaptive immunity; however, how IL-33 mediates cytotoxic T-cell regulation and the downstream signals remain elusive. In this study, we found increased mouse IL-33 expression in CD8+ T cells following cell activation via anti-CD3/CD28 stimulation in vitro or lymphocytic choriomeningitis virus (LCMV) infection in vivo. Our cell adoptive transfer experiment demonstrated that extracellular, but not nuclear, IL-33 contributed to the activation and proliferation of CD8+ , but not CD4+ T effector cells in LCMV infection. Importantly, IL-33 induced mTORC1 activation in CD8+ T cells as evidenced by increased phosphorylated S6 ribosomal protein (p-S6) levels both in vitro and in vivo. Meanwhile, this IL-33-induced CD8+ T-cell activation was suppressed by mTORC1 inhibitors. Furthermore, IL-33 elevated glucose uptake and lactate production in CD8+ T cells in both dose- and time-dependent manners. The results of glycolytic rate assay demonstrated the increased glycolytic capacity of IL-33-treated CD8+ T cells compared with that of control cells. Our mechanistic study further revealed the capacity of IL-33 in promoting the expression of glucose transporter 1 (Glut1) and glycolytic enzymes via mTORC1, leading to accelerated aerobic glucose metabolism Warburg effect and increased effector T-cell activation. Together, our data provide new insights into IL-33-mediated regulation of CD8+ T cells, which might be beneficial for therapeutic strategies of inflammatory and infectious diseases in the future.

CCR7/dendritic cell axis mediates early bacterial dissemination in Orientia tsutsugamushi-infected mice.

Scrub typhus is a life-threatening zoonosis caused by the obligate intracellular bacterium Orientia tsutsugamushi (Ot) that is transmitted by the infected larvae of trombiculid mites. However, the mechanism by which Ot disseminates from the bite site to visceral organs remains unclear; host innate immunity against bacterial dissemination and replication during early infection is poorly understood. In this study, by using an intradermal infection mouse model and fluorescent probe-labeled Ot, we assessed the dynamic pattern of innate immune cell responses at the inoculation site. We found that neutrophils were the first responders to Ot infection and migrated into the skin for bacterial uptake. Ot infection greatly induced neutrophil activation, and Ot-neutrophil interaction remarkably promoted cell death both in vitro and in vivo. Depletion of neutrophils did not alter bacterial dissemination in mice, as evidenced by similar bacterial burdens in the skin and draining lymph nodes (dLN) at day 3, as well as in the lungs and brains at day 14, as compared to the control mice. Instead, dendritic cells (DCs) and macrophages played a role as a Trojan horse and transmitted Ot from the skin into dLN. Importantly, the absence of homing receptor CCR7 or neutralization of its ligand, CCL21, significantly impaired DC migration, resulting in reduced bacterial burdens in dLN. Taken together, our study sheds light on a CCR7/dendritic cell-mediated mechanism of early Ot dissemination and provides new insights into therapeutic and vaccine development strategies for scrub typhus.

Mucosal vaccination induces protection against SARS-CoV-2 in the absence of detectable neutralizing antibodies.

A candidate multigenic SARS-CoV-2 vaccine based on an MVA vector expressing both viral N and S proteins (MVA-S + N) was immunogenic, and induced T-cell responses and binding antibodies to both antigens but in the absence of detectable neutralizing antibodies. Intranasal immunization with the vaccine diminished viral loads and lung inflammation in mice after SARS-CoV-2 challenge, which correlated with the T-cell response induced by the vaccine in the lung, indicating that T-cell immunity is also likely critical for protection against SARS-CoV-2 infection in addition to neutralizing antibodies.

Type I Interferon Promotes Humoral Immunity in Viral Vector Vaccination.

Recombinant viral vectors represent an important platform for vaccine delivery. Our recent studies have demonstrated distinct innate immune profiles in responding to viral vectors of different families (e.g., adenovirus versus poxvirus): while human Ad5 vector is minimally innate immune stimulatory, the poxviral vector ALVAC induces strong innate response and stimulates type I interferon (IFN) and inflammasome activation. However, the impact of the innate immune signaling on vaccine-induced adaptive immunity in viral vector vaccination is less clear. Here, we show that Modified Vaccinia Ankara (MVA), another poxviral vector, stimulated a type I IFN response in innate immune cells through cGAS-STING. Using MVA-HIV vaccine as a model, we found that type I IFN signaling promoted the generation of humoral immunity in MVA-HIV vaccination in vivo. Following vaccination, type I IFN receptor-knockout (IFNAR1-/-) mice produced significantly lower levels of total and HIV gp120-specific antibodies compared to wild-type (WT) mice. Consistent with the antibody response, a type I IFN signaling deficiency also led to reduced levels of plasma cells and memory-like B cells compared to WT mice. Furthermore, analysis of vaccine-induced CD4 T cells showed that type I IFN signaling also promoted the generation of a vaccine-specific CD4 T-cell response and a T follicular helper (Tfh) response in mice. Together, our data indicate a role for type I IFN signaling in promoting humoral immunity in poxviral vector vaccination. The study suggests that modulating type I IFN and its associated innate immune pathways will likely affect vaccine efficacy. IMPORTANCE Viral vectors, including MVA, are an important antigen delivery platform and have been commonly used in vaccine development. Understanding the innate host-viral vector interactions and their impact on vaccine-induced immunity is critical but understudied. Using MVA-HIV vaccination of WT and IFNAR1-/- mice as a model, we report that type I IFN signaling promotes humoral immunity in MVA vaccination, including vaccine-induced antibody, B-cell, and Tfh responses. Our findings provide insights that not only add to our basic understanding of host-viral vector interactions but also will aid in improving vaccine design by potentially modulating type I IFN and its associated innate immune pathways in viral vector vaccination.

Vertical profiling of black carbon and ozone using a multicopter unmanned aerial vehicle (UAV) in urban Shenzhen of South China.

Existing studies on vertical profiling of black carbon (BC) and ozone (O3) were mainly conducted in the rural areas, leading to limited knowledge of their vertical distributions in the urban area. To fill this knowledge gap, vertical profiling (0-500 m and 0-900 m, AGL) of BC and O3 was conducted in a highly urbanized area of Shenzhen in subtropical South China using a multicopter unmanned aerial vehicle (UAV) platform. In total 32 flights were conducted from the 10th to 15th, December 2017 (winter campaign) and 42 flights from the 19th to 28th, August 2018 (summer campaign) with 4 time slots per day, including morning, afternoon, evening, and midnight. In general, equivalent BC (eBC) concentration decreased as the height increased with an overall slope of -0.13 µg m-3 per 100 m in the winter campaign and -0.08 µg m-3 per 100 m in the summer campaign. On the contrary, an increase of O3 level with altitude was observed (7.8 ppb per 100 m). Absorption Ångström exponent (AAE) exhibits a slightly increasing trend with height. Seasonality of eBC vertical profiles was observed in morning, afternoon and midnight flights, but not for evening flights. The analysis showed the shape of vertical profiles of eBC and O3 can be affected by planetary boundary layer height (PBLH) and air mass origin. Calculated heating rates due to BC show distinct seasonal variability for morning but not for afternoon, because of the counteracting effects by solar irradiance in the subtropical afternoon and eBC concentration in urban South China influenced by the monsoon climate.

Metformin Modulates T Cell Function and Alleviates Liver Injury Through Bioenergetic Regulation in Viral Hepatitis.

Metformin is not only the first-line medication for the treatment of type 2 diabetes, but it is also effective as an anti-inflammatory, anti-oxidative and anti-tumor agent. However, the effect of metformin during viral hepatitis remains elusive. Using an adenovirus (Ad)-induced viral hepatitis mouse model, we found that metformin treatment significantly attenuated liver injury, with reduced serum aspartate transaminase (AST) and alanine transaminase (ALT) levels and liver histological changes, presumably via decreased effector T cell responses. We then demonstrated that metformin reduced mTORC1 activity in T cells from infected mice, as evidenced by decreased phosphorylation of ribosome protein S6 (p-S6). The inhibitory effects on the mTORC1 signaling by metformin was dependent on the tuberous sclerosis complex 1 (TSC1). Mechanistically, metformin treatment modulated the phosphorylation of dynamin-related protein 1 (Drp-1) and mitochondrial fission 1 protein (FIS1), resulting in increased mass in effector T cells. Moreover, metformin treatment promoted mitochondrial superoxide production, which can inhibit excessive T cell activation in viral hepatitis. Together, our results revealed a protective role and therapeutic potential of metformin against liver injury in acute viral hepatitis via modulating effector T cell activation via regulating the mTORC1 pathway and mitochondrial functions.